1. Field of the Invention
The present invention relates to image capturing apparatuses and control methods thereof, and particularly relates to image capturing apparatuses and control methods thereof that enable a pair of signals based on light beams that have passed through different pupil regions of an optical system to be read out from at least part of pixels.
2. Description of the Related Art
Heretofore technologies have been known that achieve a focus detection function and image signal obtainment using a single image sensor, and as one example thereof, a technology has been proposed (for example, see Japanese Patent Laid-Open No. 2007-325139) in which pixels used for obtaining information for focus detection can also be used as image-obtaining pixels for obtaining image signals. According to this technology, pixels for obtaining information are divided into four in the horizontal and vertical directions and, when obtaining an image, the signals of the region divided into four are all added to obtain an image signal. Furthermore, when performing a focus adjustment, by adding the signals by two regions of the four divided regions in the horizontal or vertical directions, it is possible to perform pupil-division within the pixel and use thus obtained signals for focus adjustments of a phase difference method.
However, in the configuration described in Japanese Patent Laid-Open No. 2007-325139, when performing a focus adjustment, a region that has been divided into two either vertically or laterally within the region divided into four undergoes addition processing and is read out. For this reason, in a case where division into two has been performed laterally for example, phase differences are less apparent when the main subject targeted for focusing is a horizontal line or a diagonal line having a shallow angle, and sometimes appropriate phase difference method focus adjustments cannot be carried out on the main subject.